Start the Calculation
Enter your target uptime, review period, downtime inputs, and incident count. The calculator will show SLA status, downtime budget, MTTR, chart data, and download options above the form.
Calculator
Example Data Table
| Period | Target | Recorded Downtime | Excluded Maintenance | Billable Downtime | Allowed Downtime | Status |
|---|---|---|---|---|---|---|
| 30-Day Month | 99.900% | 35 min | 0 min | 35 min | 43.2 min | Within SLA |
| 30-Day Month | 99.950% | 30 min | 5 min | 25 min | 21.6 min | SLA Breached |
| 365-Day Year | 99.990% | 40 min | 0 min | 40 min | 52.56 min | Within SLA |
| 1 Week | 99.500% | 20 min | 0 min | 20 min | 50.4 min | Within SLA |
These examples illustrate how the same uptime promise creates different downtime budgets across common cloud and hosting review windows.
Common SLA Reference
| SLA Target | Allowed Downtime in 30-Day Month | Allowed Downtime in 365-Day Year |
|---|---|---|
| 99.000% | 432 min (7h 12m) | 5256 min (3d 15h 36m) |
| 99.900% | 43.2 min (43.2m) | 525.6 min (8h 45.6m) |
| 99.950% | 21.6 min (21.6m) | 262.8 min (4h 22.8m) |
| 99.990% | 4.32 min (4.32m) | 52.56 min (52.56m) |
| 99.999% | 0.43 min (0.43m) | 5.26 min (5.26m) |
Formula Used
Allowed Downtime = Total Period Minutes × (100 − SLA Target) ÷ 100
Billable Downtime = Max(Recorded Downtime − Excluded Maintenance, 0)
Actual Availability = ((Total Period Minutes − Billable Downtime) ÷ Total Period Minutes) × 100
Remaining Budget = Allowed Downtime − Billable Downtime
MTTR = Billable Downtime ÷ Incident Count
How to Use This Calculator
- Enter the uptime target promised in your SLA, such as 99.9% or 99.99%.
- Select the review period used in your contract, or choose custom days.
- Enter recorded downtime in hours and minutes for the selected period.
- Add any maintenance minutes that are contractually excluded from uptime reporting.
- Enter the number of incidents if you want an estimated MTTR value.
- Submit the form to view availability, remaining error budget, compliance status, downloads, and the chart above the form.
FAQs
1. What does uptime SLA mean?
Uptime SLA is the promised minimum service availability for a period. A 99.9% SLA means downtime must stay below the allowed budget for that month, year, or custom window after applying any valid exclusions.
2. Why does period selection matter?
Allowed downtime depends on total minutes in the measurement window. The same SLA target permits far less downtime in a day than in a year, so you should match the calculator period to your contract.
3. Should planned maintenance be excluded?
Many contracts exclude approved maintenance from billable downtime, but not all do. Enter only the exclusions your agreement allows. If your provider counts maintenance against uptime, leave the exclusion field at zero.
4. What is error budget?
Error budget is the downtime allowance created by the SLA target. For 99.95% availability, the budget is 0.05% of the selected period. Teams use it to balance reliability work, releases, and operational risk.
5. How is MTTR used here?
This calculator estimates MTTR as billable downtime divided by incident count. It helps show average recovery speed, but it does not replace deeper incident reviews, severity weighting, or service-level objective tracking.
6. What if actual downtime exceeds total period?
If entered downtime exceeds the full period, the calculator caps effective uptime at zero and marks the result non-compliant. This prevents negative availability and keeps the report readable.
7. Can I use custom days?
Yes. Custom days are useful for billing cycles, pilot contracts, or nonstandard review windows. The calculator converts your chosen days into minutes, then applies the same SLA formulas.
8. Which SLA targets are common in hosting?
Common hosting and cloud targets include 99%, 99.9%, 99.95%, 99.99%, and 99.999%. Higher targets sharply reduce the allowed downtime budget, especially across short measurement windows.